Webbing winding device

ABSTRACT

A webbing take-up device 10 which takes up a webbing which is attached by a vehicle occupant, comprising: a rotor member 50 which rotates integrally with a take-up shaft 14 which takes up the webbing; a lock wheel 32 which is rotatably supported at the take-up shaft 14 and which rotates relatively with the take-up shaft 14, thereby deterring the take-up shaft 14. from rotating in a direction in which the webbing is pulled out; a slider 70 which engages the rotor member 50 and the lock wheel 32 with each other so as to deter the take-up shaft 14 and the lock wheel 32 from rotating relatively with each other between a state in which almost an entire amount of the webbing is taken up by the take-up shaft 14 and a state in which the entire amount of the webbing is taken up by the take-up shaft 14. As a result, it is possible to prevent end lock reliably.

TECHNICAL FIELD

The present invention relates to a webbing take-up device equipped withwebbing sensitive type lock means having an end lock preventionmechanism.

BACKGROUND ART

In a webbing take-up device with which a vehicle is equipped, there isprovided a webbing take-up device having so-called webbing sensitivetype (WSIR: Webbing Sensitive Inertia Reel) lock means in which, inaccordance with a rapid pulling out of a webbing, rotation of a lockwheel is delayed, a take-up shaft and the lock wheel rotate relativelyto each other, the lock means operates, the take-up shaft is stoppedfrom rotating in a direction in which the webbing is pulled out, and thewebbing is instantaneously prevented from being pulled out.

In this webbing sensitive type webbing take-up device, when an operationof the lock means is canceled, the operation of the lock means iscancelled by rotating the take-up shaft in a small amount in thedirection in which the webbing is pulled out.

However, when fastening of the webbing is released by a vehicleoccupant, since the take-up shaft is energized by energizing means inthe direction in which the webbing is taken up, when the vehicleoccupant unfastens the webbing, the webbing may be rapidly taken up. Insuch a state, when the taking up of the webbing has been completed, therotation of the take-up shaft is rapidly terminated. The webbing take-updevice is thereby in the same state as that when the webbing is rapidlypulled out, and there are cases in which the lock means operates.

In this case, the webbing is set in a state in which the entire amountof the webbing is taken up. There is no longer any allowance for thetake-up shaft to rotate in the direction in which the webbing is takenup. Accordingly, there arises a drawback (end lock) in which it becomesdifficult to release the lock means.

Therefore, conventionally, there has been proposed a webbing take-updevice that solves this drawback (Japanese Patent Application Laid-Open(JP-A) No. 62-95058).

With reference to FIG. 17, a webbing take-up device of this type will bedescribed hereinafter. A lock wheel 306 is rotatably supported at oneend portion 304A of a take-up shaft 304 for taking up a webbing 302. Apair of lock plates 312 are disposed at the lock wheel 306. The pair oflock plates 312 mesh with an internally toothed gear 310 which is fixedto a frame 308, and thereby prevents the rotation of a take-up shaft 14.Further, a rotor 314, which rotates integrally with the take-up shaft304, is connected to the one end portion 304A of the take-up shaft 304.A boss portion 316A of a cam 316 is inserted into the rotor 314. The cam316 can rotate due to a frictional force between the rotor 314 and thecam 316. This cam 316 is held by a friction spring 320 provided at acover body 318 by a force that is stronger than the frictional forcebetween the rotor 314 and the cam 316.

A twisting coil spring 322 is disposed between the lock wheel 306 andthe rotor 314. The twisting coil spring 322 energizes the lock wheel 306in the direction in which the webbing is pulled out (the direction ofarrow B in FIG. 17).

A protruding portion 324 is formed at the aforementioned lock wheel 306.A pawl 326 which is rotatably supported by a pin 314A of the rotor 314is able to abut this protruding portion 324.

In the webbing take-up device which is structured as described above,when the webbing is taken up, if the take-up shaft 304 rotates in thedirection in which the webbing is taken up (the direction of arrow A inFIG. 17), the rotor 314 rotates integrally with the take-up shaft 304.In this case, the rotational force of the rotor 314 is transmitted tothe cam 316 through a predetermined frictional force; however, becausethe cam 316 is held by the friction spring 320, the cam 316 does notrotate.

Therefore, one end portion 326A of the pawl 326 abuts a notched surface316B of the cam 316, and the pawl 326 thereby rotates around the pin314A as a center in the direction of arrow C. Accordingly, the pawl 326engages with the protruding portion 324 of the lock wheel 306, andthereby prevents the lock wheel 306 and the take-up shaft 304 fromrotating relatively with each other.

As a result, when all of the webbing is taken up, since the take-upshaft 304 is not locked by the lock plates 312, the webbing 302 can bepulled out easily.

In a webbing take-up device having such a conventional end lockprevention mechanism as described above, because the cam 316 is solelyheld by the friction spring 320, when the webbing is rapidly taken up,the cam 316 rotates by the frictional force between the rotor 314 andthe cam 316, and end lock is thereby caused.

DISCLOSURE OF THE INVENTION

In view of the aforementioned, it is an object of the present inventionto newly provide a webbing take-up device having webbing sensitive typelock means in which, even when an entire amount of the webbing is takenup rapidly, the webbing sensitive type lock means operates reliably.Accordingly, it is possible to prevent end lock.

In accordance with a first aspect of the present invention, there isprovided a webbing take-up device, comprising: a frame which is mountedto a vehicle; a take-up shaft which is axially supported at the frame,and which takes up a webbing for restraining a vehicle occupant; a lockwheel which following rotates around the take-up shaft, and whichrotates relatively with the take-up shaft due to rapid rotation of thetake-up shaft; lock means which prevents the take-up shaft from rotatingin a direction in which the webbing is pulled out when the lock wheeland the take-up shaft rotate relatively with each other; a planet gearwhich revolves around an axis core of the take-up shaft due to rotationof the take-up shaft and transmits reduced rotation of the take-up shaftas a revolution rotational frequency; and end lock preventing meanswhich is driven in accordance with revolution of the planet gear andprevents the lock wheel and the take-up shaft from rotating relativelywith each other in between a state in which almost the entire amount ofthe webbing is taken up by the take-up shaft and a state in which theentire amount of the webbing is taken up by the take-up shaft.

Since the present invention is structured as described above, the endlock preventing means deters the take-up shaft and the lock wheel fromrotating relatively with each other, between the state in which almostthe entire amount of the webbing is taken up by the take-up shaft andthe state in which the entire amount of the webbing is taken up by thetake-up shaft. As a result, the webbing sensitive type lock meansoperates so as to prevent the webbing from causing end lock reliably.

In accordance with a second aspect of the present invention, there isprovided a webbing take-up device having webbing sensitive type lockmeans, comprising: a rotor member which rotates integrally with atake-up shaft which takes up the webbing; a lock wheel which isrotatably supported at the take-up shaft and which prevents the take-upshaft from rotating in a direction in which the webbing is pulled outwhen the take-up shaft and the lock wheel rotate relatively with eachother; a braking member which is supported by the rotor member so as tobe movable, which is inserted into an insertion portion for brakingprovided at the lock wheel so as to prevent the rotor member and thelock wheel from rotating relatively with each other, and which isremoved from the insertion portion for braking so as to allow the rotormember and the lock wheel to rotate relatively with each other; andreduction interlocking means which interlocks with rotation of thetake-up shaft, which inserts the braking means into the insertionportion for braking between a state in which almost an entire amount ofthe webbing is taken up and a state in which the entire amount of thewebbing is taken up, and which removes the braking member from theinsertion portion for braking in between a state in which almost theentire amount of the webbing is taken up and a state in which the entireamount of the webbing is pulled out.

Since the present invention is structured as described above, thereduction interlocking means interlocks with the rotation of the take-upshaft 14 when the webbing is taken up by the take-up shaft 14, andinserts the braking means into the insertion portion for braking betweenthe state in which almost the entire amount of the webbing is taken upby the take-up shaft and the state in which the entire amount of thewebbing is taken up by the take-up shaft, and prevents the rotor memberand the lock wheel from rotating relatively with each other.Accordingly, the webbing sensitive type lock means can operate so as toprevent end lock reliably.

In accordance with a third aspect of the present invention, there isprovided a webbing take-up device according to the second aspect of thepresent invention, wherein the reduction interlocking means is formed bya gear mechanism having a planet gear.

By structuring the present invention as described above, the rotation ofthe take-up shaft when the webbing is pulled out is greatly reduced bythe gear mechanism having the planet gear. It is possible to operate thebraking member reliably and structure the reduction interlocking meansin a simple manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view that illustrates a state in which anentire amount of a webbing is pulled out, in main portions forstructuring an end lock prevention mechanism of a webbing take-up devicerelating to an embodiment of the present invention.

FIG. 2 is a schematic plan view that illustrates a state in whichswitching from ALR to ELR begins, in the main portions for structuringthe end lock prevention mechanism of the webbing take-up device relatingto the present embodiment.

FIG. 3 is a schematic plan view that illustrates a state in which theswitching from ALR to ELR has been completed, in the main portions forstructuring the end lock prevention mechanism of the webbing take-updevice relating to the present embodiment.

FIG. 4 is a schematic plan view that illustrates a state in which theentire webbing has been stored, in the main portions for structuring theend lock prevention mechanism of the webbing take-up device relating tothe present embodiment.

FIG. 5 is a schematic explanation view that illustrates a gear mechanismusing a planet gear in the webbing take-up device relating to thepresent embodiment.

FIG. 6 is an exploded perspective view that illustrates a portion of thewebbing take-up device relating to the present embodiment when viewedfrom one side.

FIG. 7 is an exploded perspective view that illustrates another portionof the structure shown in FIG. 6 of the webbing take-up device relatingto the present embodiment when viewed from one side.

FIG. 8 is an exploded perspective view that illustrates the webbingtake-up device relating to the present embodiment as seen from anotherside.

FIG. 9 is a plan view that illustrates main portions associated with alock wheel in an ordinary state of the webbing take-up device relatingto the present embodiment.

FIG. 10 is a plan view that illustrates the main portions associatedwith the lock wheel during an end lock preventing operation in thewebbing take-up device relating to the present embodiment.

FIG. 11 is a plan view that illustrates the main portions associatedwith the lock wheel in a state in which the webbing take-up devicerelating to the present embodiment is locked.

FIG. 12 is a front view that illustrates lock plates in an ordinarystate of the webbing take-up device relating to the present embodiment.

FIG. 13 is a front view of main portions of the lock plates in a lockedstate, in the webbing take-up device relating to the present embodiment.

FIG. 14 is a plan view that illustrates main portions of a switchingmechanism of ALR and ELR in a state in which the entire amount of thewebbing is taken up in the webbing take-up device relating to thepresent embodiment.

FIG. 15 is a plan view that illustrates the main portions of theswitching mechanism of ALR and ELR in a state in which switching of ALRand ELR begins in the webbing take-up device relating to the presentembodiment.

FIG. 16 is a plan view that illustrates the main portions of theswitching mechanism of ALR and ELR in a state just before ALR and ELRare switched in the webbing take-up device relating to the presentembodiment.

FIG. 17 is an exploded perspective view that illustrates main portionsof a conventional webbing take-up device.

BEST MODE FOR IMPLEMENTING THE INVENTION

In a webbing take-up device according to an embodiment of the presentinvention, the webbing take-up device can usually take up and pull outthe webbing, comprises both a so-called ELR (i.e., Emergency LockingRetractor) and a so-called ALR (i.e., Automatic Locking Retractor), andhas integrally provided therein an end lock prevention mechanism. In theELR, at the time of a rapid deceleration of a vehicle, this state isdetected by an acceleration sensor, and the ELR instantaneously preventsa take-up shaft from rotating in the direction in which the webbing ispulled out. In the ALR, after an arbitrary amount of the webbing hasbeen pulled out, even when the webbing is taken up by a minimum amount,the ALR automatically prevents the webbing from being pulled outanymore, and when almost an entire amount of the webbing is taken up bythe webbing take-up device, the ALR cancels this state in which thepulling out of the webbing is prevented, thereby allowing the webbing tobe pulled out again.

As shown in FIGS. 6, 7, and 8, in the webbing take-up device body 10, aframe 12 is fixed to a vehicle body through unillustrated mountingbolts. The frame 12 has a pair of leg portions 12A which respectivelyextend from two sides thereof parallel to each other. A cover side plate15 which is shown in FIG. 7 is attached to the frame 12 at the near sideof FIG. 6. A take-up shaft 14 is rotatably supported between these legportions 12A of the frame 12. One end of a webbing 17 for restraining avehicle occupant is engaged with this take-up shaft 14.

One end portion of the take-up shaft 14 in the lengthwise directionthereof protrudes outwardly from a leg portion 12A (i.e., the legportion toward the left-hand of FIG. 6), and the internal end portion ofa coil spring 18 is engaged with this protruding portion. The externalend portion of the coil spring 18 is engaged with a spring cover 19which accommodates therein the coil spring 18 which is fixed to theaforementioned leg portion 12A. Accordingly, due to the urging forcefrom the coil spring 18, the take-up shaft 14 is energized and rotatedin the direction in which the webbing is taken up (the direction ofarrow D in FIG. 6), and the webbing 17 is taken up in a layered state.

Then, a vehicle occupant can adopt an applied webbing state by engaginga tang plate, which is not shown and which is mounted to an end portionof the webbing 17, with a buckle device mounted to the vehicle body.

As shown in FIGS. 6 to 13, the other end portion of the take-up shaft 14protrudes outwardly from a leg portion 12A (the leg portion toward theright-hand of FIG. 6), and bifurcated portions 20 which extend from thetake-up shaft 14 in a diametrical direction is formed at this protrudingportion. A pair of lock plates 22, which form a part of lock means, aredisposed between the bifurcated portions 20 and an end surface 14A ofthe take-up shaft 14.

Namely, each of the lock plates 22 is formed in a semi-circular arcshape. As shown in FIG. 12, in a state in which each of the intermediateportions of the lock plates 22 turns around the bifurcated portions 20,one side surface of each of the lock plates 22 abuts the end surface 14Ahaving a large diameter, of the take-up shaft 14. Gaps are formedbetween inner circumferential portions of the lock plates 22, and thebifurcated portions 20, and the lock plates 22 and the take-up shaft 14can move freely as is shown in FIG. 12 to FIG. 13.

A pawl portion 24 is formed at one end portion of each of these lockplates 22, and faces internal teeth of an internally toothed gear 26which is fixed to the leg portion 12A, and which, together with the lockplates 22, forms a part of the lock means. Further, pairs of pins 28 and30 are formed near the ends of each of the lock plates 22 so as toprotrude therefrom. As shown in FIGS. 9 to 11, each of the pins 28 and30 is inserted into corresponding guide holes 34 and 36 which are formedon a lock wheel 32. The lock wheel 32 is rotatably supported by thetake-up shaft 14, and can rotate relatively with the take-up shaft 14 bya predetermined angle.

This lock wheel 32 is an externally toothed ratchet wheel having a largediameter, and ratchet teeth 38 are formed at an outer circumferencethereof. As is shown in an exploded state in FIG. 8, a ring shapedinertia member 40 is attached to the inner side of the ratchet teeth 38,and is structured so as to apply an inertia force to the rotationalmotion of the lock wheel 32.

Further, insertion portions 42, each of which is formed as a U-shapedconcave portion, are provided respectively at two portions of theinertia member 40 facing each other in the diametrical direction at theinner circumferential side thereof. Guiding curved surface portions 44,each of which is convex toward an opening provided at a predeterminedposition near an opening of each of these insertion portions 42, areformed at braking portions 46. Each of the braking portions 46 isintegrally formed with the lock wheel 32, and thereby guide means areformed.

As shown in FIG. 6, a notched portion 48 for a detention engagement iscut out at a predetermined region that is closer to a tip end of thetake-up shaft 14 than the lock wheel 32, which is rotatably supported bythe take-up shaft 14. A rotor member 50, which is shown in FIGS. 7 and8, is mounted at a notched portion 48 via a round hole portion 56. Apawl 56A, which protrudes inwardly at the round hole portion 56, isfitted into the notched portion 48, and is thereby engaged with thetake-up shaft 14 so as not to be rotatable around the take-up shaft 14.

Further, a twisting coil spring 52 is disposed between the lock wheel 32and the rotor member 50 by passing the take-up shaft 14 through a coilportion thereof. One end portion of this twisting coil spring 52 isengaged with one of engaging protruding portions 54 on a side surface ofthe rotor member 50 which is fixed to the take-up shaft 14, and theother end portion is engaged with one of the braking portions 46 of thelock wheel 32. Accordingly, the twisting coil spring 52 energizes thetake-up shaft 14 to rotate continuously the lock wheel 32 in thedirection indicated by arrow E (the direction in which the webbing ispulled out).

In this way, due to the urging force from the twisting coil spring 52,the lock wheel 32 is thereby rotated, and as shown in FIGS. 9 and 12,the pins 28 and 30 of the lock plates 22 are each pushed away to endportions of the corresponding guide holes 34 and 36, respectively. Eachof the pawl portions 24 is separated from the internally toothed gear26, and the take-up shaft 14 is set in a state shown in FIG. 12 in whichthe take-up shaft 14 can rotate freely in the direction in which thewebbing 17 is pulled out (the direction of arrow E).

Further, in opposition to the urging force from the twisting coil spring52, when the lock wheel 32 rotates relatively with the take-up shaft 14and the rotor member 50 which are fixed integrally therewith (whenrotational delay of the lock wheel 32 is caused), each of the pins 28and 30 of the lock plates 22 enters a state in which they are moved toan intermediate portion of the corresponding guide holes 34 and 36, asshown in FIGS. 11 and 13. Each of the pawl portions 24 meshes with theinternally toothed gear 26. The take-up shaft 14 is deterred fromrotating in the direction in which the webbing 17 is pulled out (thedirection of arrow E).

As shown in FIGS. 1 to 5, and 7, a ring-shaped second internally toothedgear 58 is formed integrally with the rotor member 50 in the vicinity ofa peripheral portion of a disc portion 50A which is an opposite endsurface of the lock wheel 32. A rectangular groove-shaped guide groove60 which extends in a diametrical direction of the disc plate portion50A is provided at the disc plate portion 50A. Further, a guide hole 62which is a rectangular opening is formed from the round hole portion 56to a peripheral portion in a diametrical direction of the disc plateportion 50A. A pair of guide shaft table portions 64 are formed atbilateral regions of the guide groove 60 in the disc plate portion 50A.Each of the guide shaft table portions 64 is formed in a table shapehaving a circular arc surface 64A so as to protrude from the disc plateportion 50A in the axial direction of the take-up shaft 14. The facingsurfaces of the guide shaft table portions 64 are provided parallel toeach other. The circular arc surfaces 64A of the guide shaft tableportions 64 are formed so as to be concentric with the center of theround hole portion 56. Guiding circumferential table portions 66 areprovided on flat surface portions of the disc plate portion 50A towardthe inside of the second internally toothed gear 58. The guidingcircumferential table portions 66, each of which is formed in asemi-circular arc table shape having an inner curved surface 66A, extendfrom bilateral side portions of the guide groove 60 at the side at whichthe guide hole 62 is not formed. Moreover, small guiding circumferentialtable portions 68, each of which is formed in a small protruding tableshape having a curved surface 68A, are provided at the bilateral sideportions of the guide groove 60 at the side at which the guide hole 62is formed.

A slider 70 is mounted at the guide groove 60 of the disc plate portion50A so as to slide freely in a diametrical direction of the disc plateportion 50A. An elongated hole 72 is formed at an intermediate portionof the slider 70. A tubular portion of the round hole portion 56 isinserted into this elongated hole 72. Accordingly, the slider 70 canmove freely in the longitudinal direction thereof. Further, a bossportion 74 is provided so as to protrude from the slider 70 near theelongated hole 72 in a surface portion of the slider 70 thatsliding-contacts the guide groove 60.

As is shown also in FIG. 1, this boss portion 74 is formed in a tubularshape whose plane is formed in a trapezoidal shape. A side surfaceportion 74A, which inclines from a peripheral side in a diametricaldirection of the rotor member 50 toward the center thereof (aninclination toward the lower right in FIG. 1), is formed on a sidesurface of the boss portion 74 outwardly in a diametrical direction ofthe slider 70, toward the corresponding braking member 46 of the lockwheel. Further, in a state in which the boss portion 74 is inserted intothe guide hole 62, the boss portion 74 is guided by the side portionsthereof, and slides therebetween.

A table-shaped following portion 78 having a following surface 76 isprovided so as to protrude from a flat free end portion at a side of theslider 70 opposite to the side of the slider 70 at which the bossportion 74 is formed. This following portion 78 is formed into anequilateral trapezoidal frame shape whose short base sides face theelongated hole 72. The following surface 76 of the following portion 78is formed by slope surface portions 76A which incline from both ends ofthe following portion 78 toward the elongated hole 72, and a circulararc surface portion 76B, which connects these slope surface portions andwhich is concentric with the center of the elongated hole 72.

An elongated annular table-shaped inner circumferential guide tableportion 80 is provided at an outer circumferential portion of theelongated hole 72 on a side surface portion of the slider 70 having thefollowing portion 78. Both circumferential portions of the innercircumferential guide table portion 80 in the lengthwise direction ofthe slider 70 are formed as inner circumferential guide surfaces 82. Theinner circumferential guide surfaces 82 facing each other are formed oncircular arc surfaces having the same curvature as the circular arcsurfaces 64A of the guide shaft table portions 64. The innercircumferential guide surfaces 82 are disposed in an eccentric state inwhich the distance of the radius of each of the inner circumferentialguide surfaces 82 is made longer than the distance from the center ofthe elongated hole 72 to each of the inner circumferential guidesurfaces 82.

A circular arc table-shaped outer circumferential guide portion 86having an outer circumferential guide surface 84 is provided at an endportion opposite to the following portion 78 of the slider 70. The outercircumferential guide surface 84 is formed on a circular arc surfacewhich faces the elongated hole 72 side, and which is concentric with andparallel to one of the inner circumferential guide surfaces 82 whichfaces this outer circumferential guide surface 84. A guide path 87having a constant width is formed between the inner circumferentialguide surface 82 and the peripheral guide surface 84.

An annular cam plate 88 is disposed between the pair of the guide shafttable portions 64 of the rotor member 50, and the inner circumferentialguide table portion 80. The cam plate 88 operates as an arm member of aplanet gear mechanism shown in Fig. 5. As shown in FIGS. 1 to 8, aportion of the ring portion of this cam plate 88 has a width slightlysmaller than that of the guide path 87, and is formed as a circular arcthick plate shaped cam plate portion 90 which spreads fully within theguide path 87 and slides therein. A shaft hole 94 into which a shaft bar92A of a planet gear 92 is inserted is formed at a central portion ofthis cam plate portion 90.

The planet gear 92 is formed with a full-teeth gear portion 92B and amissing-teeth gear portion 92C integrally overlapping each other in thetooth thickness direction thereof. At least the full-teeth gear portion92B of the planet gear 92 meshes with the second internally toothed gear58.

As shown in FIGS. 5 to 8, and FIGS. 14 to 16, an ALR cam member 96 issupported so as to be freely rotatable at a side that is closer to thefree end of the take-up shaft 14 than the rotor member 50. A shaftcylindrical portion 98 (FIG. 7) which is formed in a cylindrical shapeto receive a shaft is provided at the center of this ALR cam member 96.A third intermediate gear 150 (FIG. 8) is provided at a surface portionof the shaft cylindrical portion 98 toward the planet gear 92. The thirdintermediate gear 150 is formed as a missing-teeth gear portion in whichtwo teeth are provided successively, and is able to mesh with themissing-teeth gear portion 92C.

A first internally toothed gear 152 is provided at an innercircumferential surface portion of a cylindrical portion concentric withthe rotational axis of the ALR cam member 96 and having a smalldiameter, of a flat surface portion at the cover side portion 15 side ofthe ALR cam member 96. Further, a braking portion 154 for anacceleration sensor is formed such that a predetermined region of anoutermost periphery arc portion of the ALR cam member 96 is formed in acircular arc shape so as to be concentric with the ALR cam member 96 andto protrude therefrom. Further, transition portions 156 with an obliqueside form, which each extends from an outermost periphery arc portion ofthe ALR cam member 96 to a peripheral portion of the braking portion 154in a smooth manner, are respectively formed at end portions of thisbraking portion 154.

Further, as shown in FIG. 14, an operation portion 158 for an ALR-ELRswitching mechanism is formed at a predetermined region of a peripheralportion of the first internally toothed gear 152 of the ALR cam member96. The operating portion 158 is formed to have a circular arc-shapedplane and a frame shape. An operation table portion 160 is formedintegrally at one end portion of this operation portion 158, and theother end portion is made as an operation end surface 158A. Thisoperation table portion 160 is formed in an almost small circular arcshape, and has operation end surfaces 160A and 160B at the two endportions thereof, respectively. A V-shaped assembly auxiliary groove 162is formed near the operation end surface 160B of the operation tableportion 160.

As is also shown in FIG. 5, a second intermediate tooth portion 166 ofan intermediate gear member 164 meshes with the first internally toothedgear 152 of the ALR cam member 96. The intermediate gear member 164comprises a second intermediate tooth portion 166 which has few teethand a small diameter, and a first intermediate tooth portion 168 whichhas many teeth and a large diameter. The second intermediate toothportion 166 and the first intermediate tooth portion 168 are formedcoaxially and integrally with each other. A shaft hole 170 is formedalong an axis core of the intermediate gear member 164. The intermediategear member 164 is disposed by a shaft pin 172 which protrudes from apredetermined position at an inner side surface of the cover sideportion 15 being inserted into the shaft hole 170.

This first intermediate tooth portion 168 meshes with a driving gear 174which is formed integrally with the free end portion of the take-upshaft 14.

As shown in FIGS. 6, 7 and 8, and FIGS. 14 to 16, an acceleration sensor176 is mounted to a rectangular opening portion 174 which is formed onthe frame 12 of the webbing take-up device body 10. Further, the ALR-ELRswitching mechanism 178 is mounted to the frame 12 adjacent to theacceleration sensor 176. In this acceleration sensor 176, a metallicspherical body 184 is placed in a dish-shaped concave portion 182 whichis disposed in the horizontal direction of a pedestal portion 180thereof. When an acceleration greater than or equal to a predeterminedvalue containing a component in the horizontal direction is applied tothe spherical body 184, the spherical body 184 rolls between slopes ofthe concave portion 182 and the concave portion 188, rotates the pawlportion 186 around a shaft supporting portion thereof, engages anengaging pawl 191, which is provided at a free end of the pawl portion186, with the ratchet teeth 38 of the lock wheel 32, and thereby detersthe ratchet teeth 38 from rotating in the direction of arrow F (thedirection in which the webbing is pulled out).

Further, in the ALR-ELR switching mechanism 178, a round shaft bar 192which is formed upright at a supporting housing 190 is inserted into ashaft cylindrical portion 196 of an operating member 194. A braking armportion 198 is formed so as to protrude from a portion in the vicinityof one end portion of this shaft cylindrical portion 196. An engagingportion 200 as a rectangular projecting portion is formed so as to beintegrated with a portion in the vicinity of a free end of this armportion 198. The engaging portion 200 engages with the ratchet teeth 38so as to deter the ratchet teeth 38 from rotating in the direction ofarrow F. Further, an engaging pin 202 which extends parallel to theaxial line of the shaft cylindrical portion 196 is formed upright at afree end portion of the arm portion 198. A compression coil spring 206is laid between this engaging pin 202 and a projecting pin 204 of thesupporting housing 190. The operating member 194 carries out a snapaction movement. Namely, the operating member 194 is energized to aposition shown in FIG. 14 in which the engaging portion 200 disengagesfrom the ratchet teeth 38, and to a position shown in FIG. 16 in whichthe engaging portion 200 engages with the ratchet teeth 38, with anintermediate point between the above-described positions as a fulcrum,in directions opposite to each other,.

Further, an arm portion to be moved 208 is formed so as to protrude froma portion near the other end portion of the shaft cylindrical portion196 of the operating member 194 so as to face the operating tableportion 160. This arm portion to be moved 208 and the braking armportion 198 are disposed so as to protrude in different directions fromeach other, to form a V-shaped plane. Moreover, the arm portion to bemoved 208 is curved from one end portion to the free end portionthereof, and is curved toward the opposite side of the braking armportion 198.

Then, in a state shown in FIGS. 14 and 15 in which the engaging portion200 is disengaged from the ratchet teeth 38, due to a movement of theALR cam member 96 which rotates in the direction opposite to arrow F,the operating end surface 160A presses the arm portion to be moved 208,and rotates this from a position shown by a solid line to a positionshown by a double-dashed chain line, in FIG. 15. Accordingly, as shownby a solid line in FIG. 16, the engaging portion 200 is set in a statein which it engages with the ratchet teeth 38.

From this state which is shown by a solid line in FIG. 16, due to amovement in which the ALR cam member 96 rotates in the direction ofarrow F, the operating end surface 158A presses the arm portion to bemoved 208, and rotates this from a position shown by a solid line to aposition shown by a double-dashed chain line, in FIG. 16. Accordingly,as is shown by a solid line in FIGS. 14 and 15, the engaging portion 200is set in a state in which it is disengaged from the ratchet teeth 38.

A method of using the webbing take-up device according to the presentembodiment having the above-described structure, and an operationthereof will be described hereinafter.

In a state before the webbing 17 is applied to a vehicle occupant, dueto the urging force from the coil spring 18, the entire amount of thewebbing 17 is taken up by the take-up shaft 14. In this state, as isalso shown in FIG. 14, the braking portion 154 of the ALR cam member 96does not allow the engaging portion 200 of the braking arm portion 198to be engaged with the ratchet teeth 38 of the lock wheel 32. Namely, inthis state, the webbing take-up device body 10 is in a mode of use forELR.

From this state, in order for the vehicle occupant to apply the webbing17, the unillustrated tang plate should be grasped and the webbing 17 ispulled out by resisting the urging force from the coil spring 18. Byengaging the tang plate with the buckle device, the vehicle occupantattains an applied webbing state and can change his or her driving stylefreely.

On the other hand, at the time of a rapid deceleration of a vehicle, thespherical body 184 carries out an inertia movement, rotates the pawlportion 186 around a shaft pin, and thereby engages the engaging pawl191 with the ratchet teeth 38. For this reason, the lock wheel 32 isprevented from rotating in the direction in which the webbing 17 ispulled out.

At this time, because the vehicle occupant also carries out an inertiamovement, the webbing is pulled out from the take-up shaft 14, thetake-up shaft 14 rotates in the direction in which the webbing is pulledout, and, thus generating rotation of the take-up shaft 14 relative withthe lock wheel 32 in the direction of arrow G and changing from thestate in FIG. 9 to the state in FIG. 11. Due to this relative rotation,the lock plates 22, which rotate together with the take-up shaft 14,move by the pins 28 and 30, of the lock plates 22, being guided by theguide holes 34 and 36 of the lock wheel 32. The pawl portions 24 meshwith the lock teeth of the internally toothed gear 26, and the take-upshaft 14 is prevented from rotating in the direction in which thewebbing is pulled out (the direction of arrow E). As a result, thevehicle occupant is reliably restrained by the webbing 17. In thisstate, as shown in FIG. 11, since the boss portion 74 and the brakingmembers 46 are separated from each other in a diametrical direction ofthe lock wheel 32, even when the lock wheel 32 rotates relatively withthe take-up shaft 14, the boss portion 74 and the braking members 46 donot interfere with each other.

In the aforementioned attached webbing state of the vehicle occupant, asshown in FIG. 14, the engaging portion 200 of the braking arm portion198 does not engage with the ratchet teeth 38 of the lock wheel 32.

The operation and movement of webbing sensitive type lock means will bedescribed hereinafter. This means operates when the webbing 17 is pulledout rapidly. Namely, when the webbing 17 is pulled out rapidly, therotor member 50 rotates together with the take-up shaft 14. However,since the lock wheel 32 contains the inertia member 40 having a largemass, it attempts to maintain a stopped state. For this reason, byresisting the urging force from the twisting coil spring 52 which islaid between the lock wheel 32 and the rotor member 50, the rotation ofthe lock wheel 32 is delayed, and the lock wheel 32 thereby rotateslater than the rotor member 50. As described above, the lock wheel 32and the rotor member 50 rotate relatively with each other in thedirection indicated by arrow G in FIG. 12. Accordingly, as shown in FIG.13, the webbing 17 is prevented from being pulled out.

The webbing take-up device 10 according to the present embodiment can beswitched to a mode of use for ALR as needed (for example, when a childseat or the like is fastened to a passenger seat). Almost the entireamount of the webbing is pulled out, and a switching operation iscarried out.

In the state shown in FIG. 14, when the webbing 17 is pulled out fromthe take-up shaft 14, the driving gear 174, the first intermediate gear168, the second intermediate gear 166, and the first internally toothedgear 152 move in response to each other so as to rotate the ALR cammember 96 in the direction opposite to arrow F as shown in FIG. 15.

As shown in FIG. 15, the webbing 17 is set in a state just before theentire amount thereof is pulled out. Further, in this state, when thewebbing 17 is pulled out, the ALR cam member 96 rotates in the directionopposite to arrow F. The operating end surface 160A of the ALR cammember 96 rotates the arm portion to be moved 208 of the operatingmember 194 from the position shown by a solid line to the position shownby a double-dashed chain line. Then, the braking arm portion 198 of theoperating member 194 is also rotated to a position shown by thedouble-dashed chain line. The engaging portion 200 of the operatingmember 194 meshes with the ratchet teeth 38, and prevents the lock wheel32 from rotating in the direction of arrow E. In addition, the ratchetteeth 38 mesh with the engaging portion 200 only when the lock wheel 32rotates in the direction of arrow F. When the lock wheel 32 rotates inthe direction opposite to arrow F, the ratchet teeth 38 are providedwith a so-called one way clutch function in which the ratchet teeth 38and the engaging portion 200 slide with each other. Even in this state,the lock wheel 32 can freely rotate in the direction opposite to arrow F(the direction in which the webbing 17 is taken up). As a result, thelock wheel 32 is prevented from rotating in the direction in which thewebbing 17 is pulled out (the direction of arrow F). Namely, the mode ofuse of the webbing take-up device 10 is switched from ELR to ALR.

In a state in which the webbing take-up device 10 is switched to ALR, asdescribed above, the take-up shaft 14 is prevented from rotating in thedirection in which the webbing 17 is pulled out; however, the take-upshaft 14 can freely rotate in the direction in which the webbing istaken up. For this reason, after an operation in which the child seat orthe like is fastened to a vehicle seat by the webbing 17 has beencompleted, the remaining webbing 17 is taken up due to the urging forceof the power coil 18, and the child seat or the like can reliably befastened to the vehicle seat.

When the webbing take-up device 10 is switched from ALR to ELR, if arequired amount of the webbing is taken up, the operating member 194 isoperated by the operating end surface 158A, and the engaging portion 200disengages from the ratchet surface 38. Accordingly, the webbing take-updevice 10 is switched from ALR to ELR.

Next, an operation and movement of an end lock prevention mechanism withwhich the webbing take-up device body 10 according to the presentembodiment is equipped will be explained hereinafter. As describedabove, in order to switch from ELR to ALR, when the entire amount of thewebbing is pulled out, the ALR cam member 96 rotates due to the movementof the gear mechanism shown in FIG. 5. The third intermediate gear 150as a missing-teeth gear is provided at this ALR cam member 96. The thirdintermediate gear 150 intermittently meshes with and interlocks with themissing-teeth gear portion 92C of the planet gear 92, and transmitsreduction. Further, in conjunction with this, the second internallytoothed gear 58 rotates in accordance with the rotation of the take-upshaft 14, and the planet gear 92 meshing with this second internallytoothed gear 58 also rotates. Then, this planet gear 92 is reduced so asto rotate the cam plate 88, which forms an arm portion of the planetgear mechanism, by an amount corresponding to the difference between therotations of the second internally toothed gear 58 and the thirdintermediate gear 150, in a large reduction ratio. As shown in FIG. 1,the cam plate member 90 presses the peripheral guide table portion 86 ina direction opposite to the following portion 78, and an end lockcancellation state (an end lock permission state) in which the bossportion 74 is removed from the insertion portion 42 is set.

In the end lock cancellation state which is shown in FIG. 1, the stateis adopted in such a manner that the cam plate portion 90 of the camplate 88 presses the peripheral table portion 86 in the direction ofarrow H, and presses the slider 70 in the direction of arrow H as shownin this figure. The boss portion 74 of the slider 70 is removed from thegap between the insertion portion 42 and the braking member 46.Accordingly, a state is adopted in which the lock wheel 32 can rotaterelatively with the rotor member 50 integrated with the take-up shaft 14at a required angle, opposing the urging force from the twisting coilspring 52.

In this state, as shown in FIG. 16, since the engaging portion 200meshes with the ratchet teeth 38, when the webbing 17 is pulled out, therotor member 50 rotates relatively with the take-up shaft 14 in thedirection of arrow E. The state changes from a state shown in FIGS. 9and 12 corresponding to FIG. 1 to a state shown in FIGS. 11 and 13.Namely, as described above, the pawl portions 24 of the lock plates 22engage with the internally toothed gear 26 so as to prevent the webbing17 from being pulled out further.

Next, in the state shown in FIG. 1 in which the entire amount of thewebbing 17 has been pulled out, when a predetermined amount which isalmost the entire amount of the webbing 17 is taken up by the take-upshaft 14, the ALR cam member 96 of FIG. 16 rotates in the direction ofarrow F, and the operating end surface 158A presses the arm portion tobe moved 208. Accordingly, the operating member 194 rotates inversely toa state shown by the solid line in FIG. 14, and a switch is made to ELR.At an initial stage of the switch to ELR, in the gear mechanism shown inFIG. 5, the cam plate 88 rotates to a state shown in FIG. 2. The camplate portion 90 slides on the slope surface portion 76B of thefollowing surface 76, presses the following portion 78, and starts topress the slider 70 in the direction opposite to arrow H.

From this state, in the state shown in FIG. 3 (corresponding to FIG. 14)in which the webbing 17 is further taken up by the take-up shaft 14, andthe switching operation from ALR to ELR has been completed, inaccordance with the movement of the slider 70 in the direction oppositeto arrow H, the boss portion 74 moves along the guide hole 62 from FIG.9 to FIG. 10, is inserted into a side surface of the insertion portion42 and the braking member 46, and is set in a state shown in FIG. 10 inwhich the take-up shaft 14 and the rotor member 50, and the lock wheel72 are prevented from operating relatively with each other.

From a state shown in FIG. 3, when the entire amount of the webbing 17is further taken up, in accordance with this movement, the cam plate 88rotates in the direction of arrow E while the cam plate 88 is beingsupported and received by the guide shaft table portion 64. The camplate portion 90 presses the circular arc surface 76B, presses thefollowing portion 78, and goes on press the slider 70 in the directionopposite to arrow H, and is set in a state shown in FIG. 4. Moreover, inthis state shown in FIG. 4, in the same manner as the above-describedstate shown in FIG. 3, a state which is shown in FIG. 10 is set in whichthe lock wheel 72 is prevented from operating relatively with thetake-up shaft 14 and the rotor member 50.

Namely, as respectively shown in FIGS. 3, 4, and 10, the webbing take-updevice changes from a state in which almost the entire amount of thewebbing is taken up, to a state in which taking-up of the entire amountof the webbing has been completed, and returns to a state in whichalmost the entire amount of the webbing is taken up. During this state,the lock wheel 32 is in a state in which it cannot rotate relativelywith the take-up shaft 14 and the rotor member 50. Meanwhile, since thelock plates 22 maintain a state shown in FIG. 12 in which the meshing ofthe lock plates 22 with the internally toothed gear 26 is cancelled,during this state, the taking-up and pulling-out operation of thewebbing 17 are not prevented.

Further, even when the pulled-out webbing 17 is rapidly taken up by thetake-up shaft 14 until the entire amount of the webbing is taken up, andthe taking-up operation is rapidly terminated, the inertia force fromthe inertia member 40 is received by the boss portion 74 between theinsertion portion 42 and the braking member 46 so as to prevent therotor member 50 and the lock wheel 72 from rotating relatively with eachother. Accordingly, it is possible to carry out reliably such aso-called end lock preventing operation as described above, through agear mechanism.

Further, in the present embodiment, in order to rotate the cam plate 88,the structure of the gear mechanism in which a large reduction ratio hasbeen realized by using the planet gear has been described. However, thepresent invention is not limited to this. An entraining transmissionmechanism, and other reduction transmission mechanisms can be employedinstead.

Industrial Applicability

As described above, the webbing take-up device according to the presentinvention is -useful for a webbing take-up device in a seat belt systemfor protecting a vehicle occupant seated on a vehicle seat in a vehiclesuch as an automobile or the like, and is particularly suitable for thewebbing take-up device having the end lock prevention mechanism.

What is claimed is:
 1. A webbing take-up device, comprising:a frame which is mounted to a vehicle; a take-up shaft which is axially supported at said frame, and which takes up a webbing for restraining a vehicle occupant; a lock wheel which following rotates around the take-up shaft, and which rotates relatively with the take-up shaft due to rapid rotation of the take-up shaft; lock means which prevents the take-up shaft from rotating in a direction in which the webbing is pulled out when said lock wheel and the take-up shaft rotate relatively with each other; a planet gear which revolves around an axis core of the take-up shaft due to rotation of the take-up shaft and transmits reduced rotation of the take-up shaft as a revolution rotational frequency; and end lock preventing means which is driven in accordance with revolution of said planet gear and prevents said lock wheel and said take-up shaft from rotating relatively with each other in between a state in which almost the entire amount of the webbing is taken up by the take-up shaft and a state in which the entire amount of the webbing is taken up by the take-up shaft, wherein said planet gear comprises a missing-teeth gear portion, which meshes with a first gear that rotates due to reduction of the rotation of said take-up shaft, and a full-teeth gear portion, which meshes with a second gear that rotates in accordance with the rotation of said take-up shaft, and revolves by the difference between rotations of said first gear and of said second gear.
 2. A webbing take-up device according to claim 1, wherein said end lock preventing means comprises:an annular cam plate member which axially supports said planet gear and which rotates axially around said take-up shaft in accordance with the revolution of said planet gear; and a slide member which moves between a first position wherein said lock wheel and said take-up shaft are prevented from rotating relatively with each other in accordance with rotation of said cam plate member, and a second position where said lock wheel and said take-up shaft are allowed to rotate relatively with each other.
 3. A webbing take-up device according to claim 2, wherein said slide member has a boss portion that engages with said lock wheel and prevents said lock wheel and said take-up shaft from rotating relatively with each other, in said first position.
 4. A webbing take-up device according to claim 3, wherein said cam plate member has an arc-shaped cam portion which presses said slide member such that said slide member moves between said first position and said second position.
 5. A webbing take-up device having webbing sensitive type lock means, comprising:a rotor member which rotates integrally with a take-up shaft which takes up said webbing; a lock wheel which is rotatably supported at said take-up shaft and which prevents said take-up shaft from rotating in a direction in which said webbing is pulled out when said take-up shaft and said lock wheel rotate relatively with each other; a braking member which is supported by said rotor member so as to be movable, which is inserted into an insertion portion for braking provided at said lock wheel so as to prevent said rotor member and said lock wheel from rotating relatively with each other, and which is removed from said insertion portion for braking so as to allow said rotor member and said lock wheel to rotate relatively with each other; and reduction interlocking means which interlocks with rotation of said take-up shaft, which inserts said braking means into said insertion portion for braking between the state in which almost an entire amount of said webbing is taken up and a state in which the entire amount of said webbing is taken up, and which removes said braking member from said insertion portion for braking in between a state in which almost the entire amount of said webbing is taken up and a state in which the entire amount of said webbing is pulled out, wherein said reduction interlocking means comprises a gear mechanism having a planet gear; said gear mechanism comprises a first gear which is provided at a rotational member and which is reduced to rotate in accordance with the rotation of said take-up shaft, and a second gear which is provided at said rotor member and which rotates in accordance with the rotation of said rotor member, and said planet gear includes a missing-teeth gear portion which meshes with said first gear and a full-teeth gear portion which meshes with said second gear, and revolves by the difference between rotations of said first gear and said second gear.
 6. A webbing take-up device according to claim 5, wherein said reduction interlocking means has an annular cam plate member which axially supports said planet gear thereat and which rotates axially around said take-up shaft in accordance with revolution of said planet gear, andsaid braking member has a slide member which moves between a first position where said lock wheel and said take-up shaft are prevented from rotating relatively with each other in accordance with rotation of said cam plate member, and a second position where said lock wheel and said take-up shaft are allowed to rotate relatively with each other.
 7. A webbing take-up device according to claim 6, wherein said slide member has a boss portion which engages with said lock wheel so as to prevent said take-up shaft and said lock wheel from rotating relatively with each other, at said first position.
 8. A webbing take-up device according to claim 7, wherein said cam plate member has an arc-shaped cam portion which presses said slide member such that said slide member moves between said first position and said second position. 